The present invention relates to the formation of wood panels from a series of wood pieces, and in particular, relates to apparatus and methods for automatically and continuously adhering the wood pieces together.
In the manufacture of various products, such as case goods in the furniture industry, it is often desirable to incorporate one or more premanufactured wooden panels in the design of the product. These panels can be made from a monolithic piece of wood or can be built up from certain discrete layers or plies of wood. Another successful approach to forming wood panels involves adhering together a collection of boards having a rectangular cross-section in an edge-to-edge configuration. For example, wooden boards having a thickness of one inch and a width of two inches can be adhered together along their narrower edges to create a panel such as the top of a kitchen table. Another example of panel made from wood pieces is a raised panel of a cabinet door.
Various apparatus have been proposed for automatically creating panels made from adhered wood pieces. For example, U.S. Pat. No. 5,240,051 discloses a dual automated clamp carrier for gluing together panels of wood from wood panel segments. The machine includes a plurality of clamp racks in which panels are clamped so that the individual panel segments can be glued together. For example, as noted in connection with the embodiment of FIG. 11, the panels are assembled manually by an operator who first must lift a completed panel from a clamp rack and then stack new panel segments into the clamps on the clamp rack to layout a new panel. (Col. 8, lines 39-41). However, a disadvantage of this approach is that the panels must first be assembled by an operator, which undesirably involves manual labor costs and the risk that the operation will become messy because the operator must handle boards having a wet adhesive applied thereto. In addition, the apparatus can only create panels of limited width (as determined by the spacing of the clamps) and does not provide for the continuous manufacture of wood paneling material.
An improvement on this conventional apparatus is embodied in a continuous gluer machine available from Radio Frequency Services, Inc. in Wilkesboro, N.C. In particular, the model CG/RF includes an infeed system for a press that allows continuous production of wooden panels. Wood pieces are supplied from the infeed system with an adhesive applied to a leading edge of the wood piece. Within the press, the leading edge of a wood piece is pressed against the trailing edge of the immediately preceding wood piece. The immediately preceding wood piece is securely clamped and held stationary while the subsequent wood piece with the adhesive applied thereto is pressed against the preceding wood piece. The adhesive is then cured to form a secure bond. Advantageously, the adhesive is curable by way of a radio frequency energy field and the apparatus includes a radio frequency generator as part of the press, which rapidly and securely cures the adhesive between the wood pieces. Thus, the model CG/RF allows the production of a xe2x80x9ccontinuous ribbonxe2x80x9d of wood panel material comprising a series of wood pieces adhered together at their edges.
While the model CG/RF has provided great advantages over conventional apparatus, the infeed system requires that the individual wood pieces be moved transversely to the machine direction when applying the adhesive to the edges of the wood pieces. An adhesive extruder is provided adjacent the main conveyor and each wood piece is fed laterally to the conveyor such that a leading edge of the wooden piece is passed along the adhesive extruder and adhesive is applied thereto. However, in the model CG/RF, wood pieces are supplied to the conveyor in a transverse direction, which can consume potentially valuable floor space adjacent the side of the conveyor. In addition, as would be appreciated by one of ordinary skill in the art, the adhesive application process is dependent on the length of the wood piece in question, which might not provide sufficient line speed.
Another limitation on conventional apparatus relates to subsequent cutting of the wood panels to a desired size. For example, conventional cutting apparatus include a saw capable of cutting in a cross-machine direction to create panels of a predetermined width from the continuous ribbon of wood panel material as the material exits the press. However, in machines that make a single ribbon of wood paneling material, these saws are not capable of easily and quickly being adjusted to cut off panels of varying widths. The ability to cut panels of different predetermined widths at an acceptable manufacturing speed would be highly desirable.
Thus, there is a need in the industry for an apparatus and method that provide continuous production of wooden panels from a series of adhered wood pieces. Such an apparatus would not only allow continuous manufacture of these panels, but would also eliminate the need to supply wood pieces transversely to the main conveyor and would provide automatic application of the adhesive to the edges of the wood pieces.
In addition, such an apparatus would also preferably be capable of cutting off panels from the continuous panel material that have different predetermined widths, and would do so at manufacturing speeds.
The present invention addresses the above needs and achieves other advantages by providing an apparatus and method for manufacturing panels from wood pieces. The apparatus includes several stations that receive, apply adhesive to, crowd, press and cure the wood pieces into a continuous wood panel. In particular, a singulation station is configured to engage an individual one of the wood pieces oriented in a cross-machine direction from an infeed station, present the wood piece to an adhesive station for adhesive application and release the wood piece for crowding at a crowding station into a batch of wood pieces. A press station downwardly presses the batch with an upper platen and further presses the batch in a downstream direction onto the continuous wood panel by extending a clamping device onto an upstream end of the batch. A radio frequency device of the press station applies radio waves to cure the adhesive between the wood pieces of the batch so as to adhere the wood pieces together and so as to adhere the batch to the continuous wood panel. A cutting station cuts predetermined lengths of individual wood panels from the continuous wood panel.
In one embodiment, the present invention includes an apparatus for adhering a plurality of variable-width wood pieces into a continuous wood panel from which can be cut a plurality of individual wood panels. The apparatus defines a machine direction and includes an infeed station, an adhesive application station, and a singulation station. The infeed station is configured to receive the wood pieces such that the wood pieces are oriented in a cross-machine direction. An adhesive applicator of the adhesive application station is capable of applying adhesive to a side of a wood piece. The singulation station is positioned in proximity to the infeed station and includes an engagement mechanism. The engagement mechanism is configured to engage one of the wood pieces oriented in the cross-machine direction at the infeed station. Further, the engagement mechanism is configured to present the wood piece to the adhesive application station. Presentation of the wood piece to the adhesive application station allows application of the adhesive to the wood piece so that the side of the wood piece to which the adhesive is applied can be adhered to an adjoining wood piece, thereby forming at least part of the continuous wood panel.
In another aspect, the engagement mechanism includes a gripper assembly that has at least one gripper with a plurality of fingers configured to open and close about one of the wood pieces. Preferably, the gripper assembly includes a shaft and the gripper is attached to the shaft. The shaft is rotatable to a first position wherein the gripper is positioned to grip the wood piece from the infeed station. The shaft is also rotatable to a second position, wherein the gripper is positioned to present the wood piece to the adhesive application station for adhesive application. More preferably, the shaft is further rotatable to a third position wherein the gripper is positioned to release the wood piece into a crowding station while maintaining orientation of the wood piece in the cross-machine direction.
In still another aspect, the gripper assembly includes four grippers positioned circumferentially about the shaft spaced 90xc2x0 apart. In such a configuration, any three of the four grippers can be simultaneously, rotatably positioned at the first, second and third positions, respectively, by the shaft. Four circumferentially spaced grippers can be grouped in a set, and several sets spaced along a length of the rotatable shaft for gripping wood pieces of variable length.
In yet another aspect, the adhesive application station further includes a gantry beam extending in the cross-machine direction above the singulation station. The adhesive applicator is mounted on the beam for powered sliding movement in the cross-machine direction along a longitudinal edge of the wood piece presented by the singulation station for adhesive application. Preferably, the adhesive applicator is further mounted for powered movement toward and away from the longitudinal edge of the wood piece presented by the singulation station. Further preferably, the adhesive applicator is an adhesive extruder.
In another embodiment, the present invention includes a crowding station positioned downstream from the adhesive application station. The crowding station includes an upstream crowding device and a downstream crowding device. Crowding of the wood pieces into a batch is accomplished by moving the crowding devices together with the wood pieces between them.
In another aspect, the crowding station further comprises a conveying surface that includes an array of parallel slats oriented in the machine direction and defining an array of parallel openings therebetween. The upstream crowding device includes a plurality of pusher fingers at spaced intervals corresponding to the array of the openings. Pushing of the batch downstream is accomplished by interdigitating the pusher fingers into the array of openings and against the upstream edge of the batch. The downstream crowding device includes a plurality of restraining fingers corresponding to the array of openings. Restraining of the batch against the pushing of the upstream device is accomplished by interdigitating the pusher fingers into the array of openings against the downstream edge of the batch of wood pieces.
In yet another embodiment, the present invention includes a press station having an upper platen and a clamping device. The upper platen is positioned to be downwardly moveable onto the batch of wood pieces and the clamping device is configured to clampingly engage edges of the batch of wood pieces. Preferably, the clamping device includes a plurality of offset clamping bars. The offset clamping bars each have a portion extending below a lower surface of the upper platen and have attached thereto a respective one of a plurality of clamping blocks. Clamping engagement of the upstream edge of the batch of wood pieces is accomplished by actuating the clamping bars so as to move the clamping blocks in a downstream direction. In another aspect, the clamping device further includes a plurality of hydraulic cylinders positioned above the lower surface of the upper platen. The hydraulic cylinders are connected to respective ones of the clamping bars and are operative to actuate the clamping bars. Preferably, the clamping station also includes a radio frequency curing device for curing the adhesive.
Thus, the present invention provides a completely automated apparatus and method for adhering together a number of random width wood pieces quickly and efficiently. Further, the continuous ribbon of wood pieces thus created can be cut to any number of desired widths for various components. As an example, the base of a drawer may be first cut having a width of 12 inches followed by two sides each having a width of 6 inches so that a subsequent assembly operation can complete the manufacture of the drawer.